Stabilization of oils



Patented July 28, 1942 2,291,214 STABILIZATION F OILS Melvin A. Dietrich, Claymont, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application March 16, 1940, Serial No. 324,318

22 Claims.

This invention relates to the stabilization of oils and particularly to inhibiting the deterioration of viscous hydrocarbon petroleum oils.

It is well known that mineral oils during use and storage are generally in contact with oxygen which causes or accelerates deterioration of the oils particularly under the action of heat or light, whereby the oils become darker in color, form products that are acidic in nature and form deposits of insoluble sludge and oxidation products. It is likewise well known that this deterioration is catalyzed by the presence of metals, such as iron, copper, cadmium and lead. The deterioration may be further accelerated by electrical fields such as are found in transformers and switches. It has been proposed to stabilize such oils and to inhibit deterioration thereof by dissolving in the oils oil-soluble chemical compounds, which, in general, affect to some extent the physical properties of the oils. It has always been considered essential that the stabilizing agents be soluble in the oil and that they be dissolved in the oil to be effective. It has also been proposed to remove acidic compounds in the oils by contacting the oils with certain oil-insoluble bases which, however, do not inhibit further deterioration of the oils.

It is an object of the present invention to provide new chemical compounds for stabilizing mineral oils. Another object is to stabilize mineral oils against deterioration by bringing the oils into contact with certain oil-insoluble compounds. A further object is to stabilize mineral oils against deterioration in the presence of metals normally tending to catalyze the deterioration of the oils. A still further object is to stabilize mineral oils against deterioration without materially affecting their physical characteristics. Other objects are to provide new compositions of matter and to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with my invention, which comprises bringing a viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, into intimate contact with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, film-forming, basic amine resin, in sufficient amounts to materially inhibit the deterioration of the oil. I have found that such resins will inhibit deterioration of the oil, even though such resins are substantially insoluble in the oil.

By a viscous oil, I mean one which has a viscosity of at least 35 seconds Saybolt at 100 F.

and intend to include gas oils, diesel oils, furnace oils andgreases, as well as the usual lubricating oils. By petroleum" oils, I meanioils derived from petroleum. By the term basic amine resin, I mean ani 'amine resin which is basic in reaction and is in'z the form of the free base and intend to exclude salts or addition products. By film-forming.resins,"I mean that they are capable of being forme'd -into a coherent film. The resins of my invention are insoluble in the petroleum oils, in water, in 2% aqueous ammonia and in 5%'aqueous sodium hydroxide. By the term dilute-alkali, as employed herein and in the claims, I mean 2% aqueous ammonia and 5% aqueous sodium hydroxide. By the term insoluble, as employed in this specification and in the claims hereinafter presented in this case, I mean that they cannot be soluble in such media to the extent of 0.5%, in other words, the solubility of the resins of my invention in such media is less than 0.5%.. A preferred class of the resins of my invention'is further characterized by being solubleto theaextent. of at least 1.0% in 5% aqueous acetic acid, and. when I employ the term dilute-acetic-acid soluble, I mean soluble to such extent in suchacid and to. include such class of resins and only such class.

The basic amine resins of my invention are amino-nitrogen containing polymeric materials. One type of such resins is represented by polymerized dialkylaminoalkyl methacrylate in which the number of carbon atoms in each alkyl group on the nitrogen atom does :not exceed 3 and which polymerized products "have the physical characteristics hereinbefore specified. sentative methacrylate polymers, which I have found to be'suitable for my purpose,.-are polymers of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Another class of suit able basic amine resins is represented .by the resinous reaction products of. alkylene-dihalides those obtained by the condensation. of aminonitriles and formaldehyde, which resinshave the physical characteristics hereinbefore specified.

An example'of a suitable resin of this last class 1 is the reaction product of hexamethylenediamine, acetone cyanhydrin. and formaldehyde.

Repre-- ,The following Examples 1 to 3 inclusive are given to. illustrate suitable methods of preparing typical resins of my invention.

, Esra-mp2s I A solution of 1 gram mol of beta-diethylaminoethanol, 4 gram mols of methyl methacrylate, 500

grams of dry benzene, and 30 grams of p-phenyl-' enediamine was prepared. This solution was heated in an oil bath under a .48" fractionating column fitted with a distillinghead arrangedfor controlling thererlux. As soon as the removal of the water, in the form of the water-benzene binary, was completed, 2 grams of sodium in 20 cc. of dry methanol were added dropwise to the chloride, and hexamethylenediamineand ethylenedichloride.

Example III One hundred seventy parts (2-.0 mols) of acetone ,cyanhydrin is added with stirring to 116 parts (1.0 mols) ofhexamethylenediamine,;the temperature being maintained at 50 C. by external cooling. The mixture, whichsoon solidifies, is allowed to stand over night and is then ground and washed thoroughly with cold water, dried, and, recrystallized from petroleum ether. The product, obtained in:90 percent yield, is 2, 2, 11, ll-tetramethyl-3, 10-diazadodecanedicarboxylonitrile.

clear and homogeneous-and.then turbid as a white, soft, rubber-like polymer precipitates.

with 95 per cent ethyl alcohol and then with water, and is finally dried in vacuo. Analysis of one sample of the resin gave the following results: N.-=19%, H--9.38%, C=62.;14%. This resin is insoluble in water and 2% aqueous ammonia,

omer to the acetate salt in aqueoussolution, ad-

lusting to 10 per cent concentration, adding 1 .per cent powdered benzoyl peroxide based on the monomer, and heating for 24 hours at 100 C. The resulting material, purified by filtration,

washing, and drying, is converted to the free polymeric base by mixing with an excess'of sodium bicarbonate and heating to liberate carbon dioxide. The precipitated polymer is insoluble in water, oil, and5per cent sodium hydroxide but I is soluble in 5 per cent aqueous acetic acid.

Example If A one-liter glass bottle, closed with'a stopper bearing an open glass tube of narrow bore, is charged with 196 parts of ethylene dichloride, 68 parts of anhydrous ammonia, 80 parts of sodium hydroxide, and 1 part of potassium iodide. The bottle is then heated in an autoclave for 10 hours at 60 C. under nitrogen pressure (Calc. 400 lbs. per sq. in.) sufficient to counter-balance the pressure developed by the heated ammonia, in order to minimize volatilization of the reactants. After cooling and opening the autoclave, the contents of the bottle are washed out with water, leaving a nearly white, gelatinous solid (15.4 parts dry weight) which is separated by filtration. In order to remove ionically bound chlorine from the resin, the insoluble gelatinous material is digested on a steam bath for,2 hours with 4 per cent sodium hydroxide and is then washed with water on a filter until the filtrate is substantially free of chloride ions and caustic as determined by tests with silver nitrate solution and with litmus paper, respectively. The resin, thus obtained, is found by analysis to contain 55.77 per cent carbon, 9.32 per cent hydrogen, 10.85 per cent nitrogen, and 4.66 per cent chlorine. This material has no detectable solubility in organic solvents, in water, in 5 per cent acetic acid or in 5 per cent sodium hydroxide. The resin (two parts) is able to absorb 0.65 part of sulfuric acid from a l/ 300 molar sulfuric acid solution. This basicity corresponds to a neutral equivalent of 150 for the resin.

Suitable resins may be made in a similar fashion using hexamethylene dibromide and ammonia, tetraethylenepentamine and ethylene di- ,but soluble in dilute aqueous acids such as 5% hydrochloric acid and acetic. acid. It'is soluble in certain organic solvents such as ethyl acetate, chloroform, dioxan, and dioxan-isobutanol mixture. It is not solublein mineral oils. 7

The basic amine resin may be dispersed in the oil to be stabilized, where desirable. Usually, the resin will not be dispersed in the oil, but the ,oil will be brought into contact with the resin by other means, such as by lining oil storage containers, such as cans, crankcases, tanks, transformers, switches and the like, or lining conduits, through which theoils flow, with such resin- Such linings need not completely cover the surfaces of the containers since it has been found that contact of the oil with the resin is suflicient to effect stabilization and that com plete exclusion of contact with other surfaces is not necessary. Further, the resin, in granulated form, may be spread over the bottom of the storage container and contact with the oil effected in this fashion. In cases where the oil is flowing, stabilization may be effected by passing all or a portion of the oil through a filter medium impregnated with the resin or through a filter cartridge containing the resin in suitable granulated form. By thus contacting the oil with the resin, which is substantially insoluble in the oil, the physical characteristics of the oil are not materially affected by the resin.

In order to illustrate the modes of employing the resins of my invention and the advantageous results to be obtained thereby, the following examples are given:

Example IV A two-ounce friction top can of galvanized steel was partially coated on the inside with polymeric diethylaminoethyl methacrylate by evaporation from acetone solution. The can was then filled two-thirds full with an asphaltic base SAE-30 oil so that the oil contacted uncoated parts of the surface of the can as well as the coating on coated parts. The can was then closed and kept at 150 C. for two days. A control sample was tested simultaneously. At the end of two days, the oil in the treated can had darkened only very slightly while that in the untreated can had become quite dark.

} p To parts of this material, parts of aqueous-37 percent formaldehyde is, added with stirring. During the course of about 7 five minutes at 22-40 C., the mixture becomes Example V The beneficial efiect of these polymers may be realized by impregnation of filters followed by passage of the oil through the filter. A piece of heavy filter cloth was soaked in an acetone solution of polymeric dimethylaminoethyl methacrylate and dried in an oven at 110 C., the final ratio being 6.8 grams of cloth to 1.47 grams of polymer. Ninety grams of asphaltic base SAE-20 oil, containing;2 per cent cocoanut oil acids, was filtered through this cloth under pressure and the change in acidity determined. A control experiment was performed using unimpregnated cloth. The results on acidity were as follows:

Neutalization number, mg. KOH/gm. oil

Unfiltered oil 3.5

Oil filtered through untreated cloth 3.1

Oil filtered through treated cloth 2.2

- Example VI In another experiment, 10 grams of an asphaltic base SAE-30 oil were placed in a 50 cc. beaker, 0.5 per cent by weight of diethylaminoethyl methacrylate polymer added, and the out fit placed in an oven at 150 C. for six hours, a control sample being tested simultaneously. At the end of this time, the oil, containing the polymer, showed very little change in color while the control sample had darkened considerably.

Example VII Example VIII Fifty grams of a parafiin base SAE-2O oil, containing in suspension 0.5 per cent by weight of the ethylene dichlorideammonia resin described in Example II, was placed in a 125 cc. Erlenmeyer flask which was heated to an average temperature of 175 C. Moist air was bubbled through the oil and strips by 1%") cut from cadmium-silver and copper-lead alloy bearings were suspended in the flasks, immersed in the oil to a depth of half their lengths. Soft steel pieces of similar size were also suspended in the oil. The bearing strips were removed at regular intervals, washed, and weighed. Loss of weight was plotted against hours of exposure and the point at which 10 mg. loss of weight per 10 grams of bearing was noted. Sludge was determined by diluting 5 grams of oil to 100 cc. volume with precipitation naphtha, chilling at 0 C. for 3 hours, filtering, and weighing the col lected sludge. The results are:

The aminonitrile-formaldehyde resin, described in Example III, was tested in a similar oil using the same procedure as given in Example VIII. This gave the following results:

Hours to 10 mg./l0 gm. loss I Sludge a mumoppersilver lead Controlno resin added Below 20 21 459. 6 Containing resin 26 44 169. 4

It will be understood that the examples, here-'- inbefore given, are for illustrative purposes only. It will be readily apparent to those skilled in the art that many variations and modifications can be made in the resins employed, the methods of making them and the methods of contacting the oil therewith without departing from the spirit or scope of my invention. For example, suitable polymeric basic amine resins within my invention are:

amineformaldehyde Diisobutyl ketone cyanhydrin-ethyienediamine-formaldehyde Dipropyl ketone cyanhydrin-1,2-propylenediamine-formaldehyde Methyl hexyl ketone cyanhydrin-butylenedlamine-formaldehyde Formaldehyde cyanhydrinpropylenediamin formaldehyde Formaldehyde cyanhydrin butylenediamineformaldehyde Formaldehyde cyanhydrin hexamethylenediamine-formaldehyde From the above. it will be apparent that the resins employed in accordance with my invention are effective not only to remove acidic compounds in the oil in a manner similar to other insoluble basic materials hereinbefore employed, but also to stabilize the oils against color formation, to inhibit formation of sludge and to inhibit the formation of corrosive products in the oils. They may be employed in the presence of other oil-modifying agents such as pour-point depressants, viscosity-index improvers, oiliness agents, and the like. However, if such other oilmodifying agents are acidic in character, the resin will eventually remove them from the oil, and this must be taken into consideration when employing such resins in the presence of such acidic oil-modifying agents.

I claim:

1. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, in intimate contact with an un'dissolved oil-insoluble, Water-insoluble, dilute-alkali-insoluble, film-forming, basic amine resin, in surficient amount to materially inhibit said deterioration of said oil.

2. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, dilute-acetic-acid-soluble, film-forming, basic amine resin, in sufficient amount to materially inhibit said deterioration of said oil.

3. A viscous hydrocarbon petroleum oil, nor mally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved, oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, polymer of a dialykylaminoalkyl methacrylate in which each alkyl group contains from 1 to 3 carbon atoms, in suflicient amount to materially inhibit said deterioration of said oil.

"4. A viscous hydrocarbon petroleum oil, nor- ,mally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved oil-insoluble, Water-insoluble, dilute-alkali-insoluble, dilute-acetic-acid-soluble, film-forming, polymer of a dialkylaminoalkyl methacrylate in which each alkyl group contains from 1 to 3 carbon atoms, in sufiicient amount to materially inhibit said deterioration of said oil.

5. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, dilute-aceticacid-soluble, film-forming, polymer of diethylaminoethyl methacrylate, in

sufficient amount to materially inhibit said deterioration of said oil.

6. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, resinous reaction product of an alkylenedihalide with a nitrogenous base, in sufficient amount to materially inhibit said deterioration of said oil.

7. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, resinous reaction product of ethylene dichloride and ammonia, in sufiicient amount to materially inhibit said deterioration of said oil.

8. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, which oil is in contact with a metal normally tending to catalyze such deterioration and which oil i s :in intimate contact with an undissolved oil-insoluble, Water-insoluble, dilute-alkali-insoluble, film-forming, basic amine resin, in sufiicient amount to materially inhibit said deterioration of said oil.

9. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, which oil is in contact with a metal normally tending to catalyze such deterioration and which oil is in intimate contact with an undissolved oil-insoluble, water-insoluble, dilutealkali-insoluble, dilute-acetic-acid-soluble, filmforming, basic amine resin, in sufficient amount to materially inhibit said deterioration of said 011.

10. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence of oxygen, which oil is in contact with a metal normally tending to catalyze such deterioration and which oil is in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, dilute-acetic-acid-soluble, filmforming, polymer of a dialkylaminoalkyl methacrylate in which each alkyl group contains from 1 to 3 carbon atoms, in sufiicient amount to materially inhibit said deterioration of said oil.

11. A viscous hydrocarbon petroleum oil, normally tending to deteriorate in the presence or oxygen, which oil is in contact with a metal normally tending to catalyze such deterioration and which oiiis in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, resinous reaction product of an alkylenedihalide with a nitrogenous base, in sufficient amount to materially inhibit said deterioration of said oil.

12. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute alkall-insoluble, film-forming, basic amine resin, in suflicient amount and for a sufficient length of time for said resin to materially inhibit said deterioration of said oil, without dissolving said resin in said oil.

13. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, dilute-acetic-acid-soluble, film-forming, basic amine resin, in sufiicient amount and for a sufficient length of time for said resin to materially inhibit said deterioration of said 011, without dissolving said resin in said oil.

14. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, film-forming, polymer of a dialkylaminoalkyl methacrylate in which each alkyl group contains from 1 to 3 carbon atoms, in sufficient amount and for a suflicient length of time for said polymer to materially inhibit said deterioration of said oil, without dissolving said polymer in said oil.

15. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in'the presence of oxygen, which comprises effecting intimate contact with the oil with an oil-insoluble, water-insoluble, dilute-alkali-insoluble, dilute-acetic-acid-soluble, film-forming, polymer of diethylaminoethyl methacrylate, in sufficient amount and for a sufficient length of time for said polymer to materially inhibit said deterioration of said oil, without dissolving said polymer in said oil.

16. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, film-forming, resinous reaction product of an al'kylenedihalide with a nitrogenous base, in sufficient amount and for a sufficient length of time for said resinous reaction product to materially inhibit said deterioration of said oil, without dissolving said resinous reaction product in said oil.

17. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, film-forming, resinous reaction product of ethylene dichloride and ammonia, in sufiicient amount and for a suflicient length of time for said resinous reaction product to materially inhibit said deterioration of said oil, without dissolving said resinous reaction product in said oil.

18. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen and catalyzed by a metal in contact therewith, which comprises effecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkaliinsoluble, film-forming, basic amine resin, in sufiicient amount and for a suflicient length of time for said resin to materially inhibit said deterioration of said oil, without dissolving said resin in said oil.

19. The method of inhibiting deterioration oi a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen and catalyzed by a metal in contact therewith, which comprises efiecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilutealkali-insoluble, dilute-acetic-acid-soluble, filmforming, basic amine resin, in suificient amount and for a suflicient length of time for said resin to materially inhibit said deterioration of said oil, without dissolving said resin in said oil.

20. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen and catalyzed by a metal in contact therewith, which comprises eifecting intimate contact of the oil with an oilinsoluble, water-insoluble, dilute-alkali-insoluble, film-forming, polymer of a dialkylaminoalkyl methacrylate in which each alkyl group contains from 1 to 3 carbon atoms, in sufiicient amount and for a sufi'icient length of time for said polymer to materially inhibit said deterioration of said oil, without dissolving said resin in said oil.

21. A viscous hydrocarbon petroleum oil, normally tending to deterioratein the presence of oxygen, in intimate contact with an undissolved oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, resinous reaction product of ethylene dichloride and tetraethylenepentamine, in sufficient amount to materially inhibit said deterioration of said oil.

22. The method of inhibiting deterioration of a viscous hydrocarbon petroleum oil, normally occurring in the presence of oxygen, which comprises efiecting intimate contact of the oil with an oil-insoluble, water-insoluble, dilute-alkali-insoluble, film-forming, resinous reaction product of ethylene dichloride and tetraethylenepentamine, in sufficient amount and for a suflicient length of time for said resinous reaction product to materially inhibit said deterioration of said oil, without dissolving said resinous reaction product in said oil.

MELVIN A. DIE'I'RICH. 

